Bearing and drive construction for gas turbine engines



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BEARING AND DRIVE CONSTRUCTION FOR GAS TURBINE ENGINES Original Filed Feb. l, 1965 l5 Sheets-Sheet 1S INVENTOR. M777 ,.B, M/f-'zf'md United States Patent O ...MMA

ABSTRACT F THE DISCLQSURE A gas turbine engine in an automotive vehicle having a bearing lubrication system utilizing turbine shafts, a gas bleed between the turbine stages, and an overrunning clutch between coaxial gears of an automatic transmission driven by the engine.

This is a division of application Ser. No. 429,600, tiled Feb. 1, 1965.

This invention relates to gas turbines, and more particularly to engines of this type especially adapted for use in automotive vehicles.Y

It is an object of the present invention to provide a novel and improved gas turbine which may be mounted in the rear portion of a vehicle beneath the deck, thereby eliminating the need for exhaust ducts extending beneath the vehicle and greatly simpli-fying the power train.

It is another object to provide an improved regenerative gas turbine of this character in which the regenerator matrices are on axes spaced laterally from and transverse to the turbine axis, thus creating a relatively dat overall configuration for the unit which has space location advantages.

It is a further object to provide an improved gas turbine of this nature which may be constructed largely of pairs of sheet metal stampings with the joints being brazed, thus facilitating inexpensive high quantity production.

It is also an object to provide an improved gas turbine having these characteristics, in which the temperature of the outside of the unit will be no higher than that of the exhaust gases emitted from the regenerators, thus minimizing heat losses and insulation problems, as well as reducing radiation to adjacent parts.

It is another object to provide an improved gas turbine of this nature which eliminates the need for external oil lines for either the front or rear bearings of the compressor and power shafts, utilizing instead compressed air which aids in transmitting oil to the bearings along an internal path.

It is also an object to provide an improved gas turbine of this character in which proper bearing support is insured -for the power shaft when it is in stalled condition and thus has its highest bearing load, the construction preventing breakdown of the hydrodynamic load-carry ing oil lm in the forward power shaft bearin g.

It is a further object to provide an improved gas turbine of this nature which incorporates a bleedoi valve between the rst and second stages, thus reducing the power and fuel rate at idle when the load is braked but still connected to the second stage, and permitting idling at a lower compressor speed.

It is another object to provide an improved gas turbine having these characteristics, in which the entire turbine housing is secured to its support at only one end, thus eliminating expansion and contraction problems arising from temperature variations during operations.

It is also an object to provide a gas turbine of this 3,377,198 Patented Apr. 16, 1968 ICC character in which the regenerators and seals may be easily removed from or inserted into the housing without disturbing the engine structure or alignment of cornponents, the means for accomplishing this object comprising removable doors on the low pressure exhaust duct, thus eliminating the need for heavy ilanged and bolted joints in the high pressure `duct system.

It is another object to provide an improved combination of a gas turbine engine with a vehicle having an automatic transmission, which utilizes a conventional concentric gear arrangement for the transmission power and oil pump drives to connect the power drive with the turbine compressor, thereby permitting use of the compressor as a brake to prevent excessive second stage turbine speeds.

It is a further object to provide an improved regenerator gas turbine of this type in which novel means are provided for driving the rotary regenerator matrices in such a way as to allow for relative movement of the parts due to temperature variations.

Other objects, features and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings.

In the drawings:

FIGURE l is a side elevational view of the rear portion of an automotive vehicle showing the location of the improved gas turbine therein;

FIGURE 2 is a rear elevational View of the automotive vehicle;

FIGURE 3 is a top plan view of the vehicle;

FIGURE 4 is a plan View in cross section showing the internal construction of the gas turbine, parts being broken away;

FIGURE 5 is a sectional plan view in the vicinity of one of the regenerator matrices taken along the line 5 5 of FIGURE 6;

FIGURE 6 is a cross-sectional view of the regenerator structure taken along the line 6 6 of FIGURE 3;

FIGURE 7 is an enlarged fragmentary view in cross section of the rear bearing portion of the turbine taken in the area marked 7 of FIGURE 4, the view, however, being in elevation instead of in plan;

FIGURE 8 is a cross-sectional view taken along the line 8 8 of FIGURE 4 and showing the bypass valve between the first and second stages;

FIGURE 9 is a front end elevational view of one of the stampings which comprises the main turbine housing; FIGURE 10 is a top plan view 0f this stamping;

FIGURE l1 is a cross-sectional view in elevation of this housing taken along the line 11 11 of FIGURE 10;

FIGURE 12 is a rear end elevational view of one of the stampings of the pair which form the duct leading compressed air to the regenerators;

FIGURE 13 is a top plan View of this stamping;

FIGURE 14 is a cross-sectional view of this stamping taken along the line 14-14 of FIGURE 13;

FIGURE 15 is a rear end elevational view of one of the stampings of the pair which -form ducts leading heated air from the regenerators to the burner;

FIGURE 16 is a top plan view of this stamping;

FIGURE 17 is a cross-sectional view in elevation of this stamping taken along the line 17 17 of FIGURE 16;

FIGURE 18 is a front end Velevational view of one of the stampings of the pair which form ducts leading the burned gases from the exhaust diffuser to the regenerators;

FIGURE 19 is a top plan view of the stamping;

FIGURE 20 is a cross-sectional view in elevation taken along the line 20 20 0f FIGURE 19;

FIGURE 21 is an elevational view in cross section showing the construction within the gear box as well as the connections to the automatic transmission and a portion of the drive for the rear wheels of the vehicle;

FIGURE 22 is a partially schematic end elevational view of the gearing within the gear box taken along the line 22-22 of FIGURE 21;

FIGURE 23 is a cross-sectional view of the gearing taken along the line 23-23 of FIGURE 22;

FIGURE 24 is a fragmentary cross-sectional View taken along the line 24-24 of FIGURE 21 and showing the overrunning clutch;

FIGURE 25 is a plan cross-sectional view taken along the line 25-25 of FIGURE 22 and showing the chainand sprocket connection for the core drive;

FIGURES 26 to 28 are views similar to FIGURES 1 to 3 respectively, but showing a modified positioning for the intake air grills especially suitable for station wagons; and

FIGURES 29 to 31 are views similar to FIGURES l to 3 showing another embodiment of the air intake arrangement in which the curved ducts extend directly from the intake grill to a pair of opposite-ly disposed intake chambers attached to the turbine housing.

Briey, the illustrated embodiment of the invention comprises a gas turbine engine having a power shaft surrounded by a compressor shaft, with an annular burner surrounding these shafts. The discharge from the radial compressor is fed outwardly to opposite sides of the engine, where it enters four rotary type axial ow regenerators. These regenerators are mounted in two coaxial pairs disposed on opposite sides of the main turbine axis, the two axes of the regenerator pairs being perpendicular to and spaced a considerable distance from the turbine axis. The regenerators of each pair are vertically spaced from each other along their axis. The entire unit has a general or overall configuration slightly resembling a T, that is, the height of the housing is no greater than that needed to accommodate the compressor, burner and turbine wheels, those portions of the housing enclosing the exhaust passages and heat exchanger pairs extending rearwardly and to both sides of the housing portion which encloses the compressor, burner and turbine wheels.

The engine is mounted in the rear portion of an automotive vehicle below the deck, the exhaust gases emitted from the engine being led downwardly and rearwardly from the rearward portions of the housing wings which enclose the regenerators. The exhaust gases may thus be led directly to the atmosphere without the need for additional ducts. The intake air may be fed through grills on the after portion of the vehicle and ducts which pass around both sides of the engine housing and return beneath the engine through a silencer and filter arrangement disposed beneath the engine housing, and thence enter the compressor intake chamber.

The housing is composed mainly of four pairs of sheet metal stampings, the stampings in each pair being substantially identical with open sides facing each other and edges which are in either abutting or overlapping relation and are brazed together. One pair of stampings, referred to as ahe main housing stampings, serves as the main outer rearward portion of the housing and conducts exhaust gases exiting from the regenerator pairs to the atmosphere. A second pair of stampings, referred to as the compressed air duct stampings, leads the air delivered from the compressor to the spaces above and below the forward portions of each pair of regenerators so that this air may iiow into the regenerators.

A third pair of stampings, referred to as the heated air duct stampings, has wings disposed in the spaces between the regenerators of the two pairs forwardly of their axes and receives the heated air delivered from the regenerators conducting this air to a chamber surrounding the burner. A. fourth pair of stampings, called the exhaust gas duct stampings, encloses the exhaust gas diffuser which leads 4 from the second stage turbine wheel and has wings disposed between the regenerators of the two pairs rearwardly of their axes, delivering the hot exhaust gases to the two regenerators. The main housing stampings form chambers above and below the regenerators rearwardly their axes for receiving the exhaust gases exiting from the regenerators and delivering them to the atmosphere. Except for the relatively small annular area of an intermediate support ring, the only portions of the housing which are exposed to the atmosphere are those of the main housing stampings and of the compressed air stampings. No substantial portion of the outer housing surface will therefore be at a temperature higher than that of the cooled exhaust gases leaving the regenerators, and the need for heat insulation is thus largely eliminated.

"Ehe rear wall portions of the main housing stampings are provided with openings having arcuate covers removably secured thereto. Removal of these covers permits access to the regenerator cores and their adjacent seals, which may be inserted or removed by merely slipping them into and out of the housing, without disturbing the structure or alignment of the remaining engine components.

The turbine housing is secured to and supported by a gear box housing disposed forwardly thereof. The power shaft is rotatably mounted within the compressor shaft, the forward bearing of the latter being supported directly by the gear box housing. The forward ends of the compressed air duct stampings are also secured to the gear box housing. An annular ring secured to the rearward portions of the compressed air duct stampings supports the burner and the turbine wheel shroud, the latter in turn supporting the rear bearings of the compressor and power shafts through the second stage nozzles, an inner turbine wheel shroud, and a ring of relatively thin cross section disposed kbetween the inner shroud and the member which directly supports the bearings. The latter is a massive member disposed within an annular oil collection chamber and also acts as a heat sink for oil entering the chamber from the rear shaft bearings. The thin ring carries the main temperature gradient, thus insuring concentricity of the assembly.

Means are provided for insuring a completely internal oil circulating system for the rear as well as the forward shaft bearings. The oil for the rear bearings is fed rearwardly from a reservoir in the gear box through the power shaft by means of an oil pump and the effect of power shaft rotation. The oil lubricates the rear bearings and then passes into the collection chamber mentioned above. At the same time, air pressure is bled from the compressor diffuser through an annular passage between two coaxial parts of the compressor shaft to the collection chamber. An oil return passage is provided in the lower portion of the rear bearing support leading from the collection chamber to the annular space between the power and the compressor shafts. The compressed air will force the oil from the collection chamber through the return passage and into this annular space. The forced oil will be forced by rotation of the compressor shaft through the turbine to the reservoir. Upon shutdown, damage to oil collecting in the chamber will be prevented by the presence of the heat sink.

The compressor shaft supports the forward bearing of the power shaft, which is a sleeve bearing. This will insure proper bearing support for the power shaft when it is stalled with high torque and therefore exerts maximum load on its bearing, since the compressor shaft will keep rotating and therefore maintain the hydrodynamic load-carrying lm.

A bleedoff or bypass valve is provided between the first stage turbine wheel and the second stage nozzle vanes, this bleedolf valve taking the form of radial apertures in the outer shroud, these apertures being covered by a band of flat cross-sectional shape which may be slightly lifted to open the apertures. Since during idling the rear wheels will be braked but still connected to the second stage turbine wheel, a predetermined back pressure would normally exist at the first stage turbine wheels. Opening of the bleedoi valve will decrease this back pressure, thereby permitting the gas temperature into the first stage to be reduced for the same first stage speed. Since the lower gas temperature can be obtained with a lower fuel flow rate, the result will be that less fuel will be used at idling speeds than would be necessary without the bleedoif valve.

The compressor shaft is used to drive accessories including an automatic transmission oil pump. The power shaft is connected to the automatic transmission, and a conventional arrangement is used wherein the drives for the transmission oil pump and power are through concentric gears. An overrunning clutch is placed between these concentric gears, which rotate at relative speeds such that the clutch will normally be inoperative. However, should the power train reach an excessive speed (for example, with the rear wheels spinning on ice) which might cause damage to the second stage turbine wheel or other parts, the overrunning clutch will serve to connect the power train to the turbine compressor, thus in effect braking the power train.

The regenerator matrix shafts are connected to the driving train by a chain and sprocket arrangement which, because of its size tolerances, will insure proper matrix rotation -despite relative movements of parts of the turbine components due to temperature variations.

Referring more particularly to the drawings, and particularly to FIGURES l to 3, the reference numeral 21 indicates generally an automotive vehicle having rear wheels 22 and a rear deck 23 beneath which is mounted the gas turbine engine generally indicated at 24. An air intake grill 25 is provided between the rear window 26 of the vehicle and the truck hood 27, a pair of ducts 28 and 29 leading laterally and rearwardly from the grill and alongside the walls of the trunk to a chamber 31 at the rear of the vehicle. It should be noted that FIG- URES 1 to 3 do not fully show portions of the vehicle adjacent the gas turbine, these being merely shown in phantom lines. The length of ducts 28 and 29 will permit trapping of moisture in the intake air. A duct 32 leads downwardly and forwardly from chamber 31 centrally of the vehicle, this duct leading to an air filter and silencer chamber 33 beneath turbine 24. This chamber is of large enough size to accommodate a silencing and filtering unit 34 through which the air flows, the air then being conducted upwardly through a duct 35 to a compressor inlet chamber 36, seen in FIGURE 4.

Exhaust gases from the turbine are fed downwardly and rearwardly from the main turbine housing indicated generally at 37 in FIGURE 6, through louvers 38 in thishousing to a pair of exhaust discharge ducts 39 of downwardly and rearwardly flared shape, these ducts having rearwardly facing openings 40. As will be seen in FIG- URES 1 and 2, openings 40` are immediately adjacent the underside of the rear end of the vehicle, so that the exhaust gases need not be conducted further by means of conduits lbut may be emitted directly to the atmosphere.

The general arrangement of the turbine itself is perhaps best seen in FIGURE 3. The exterior of the housing is mainly formed by main housing 37, together with a cornpressed air housing generally indicated at 41 and a gear box housing generally indicated Iat 42. These housings are in Igeneral alignment along the longitudinal axis of the turbine, but housings 37 and 41 also extend laterally to both sides, forming what might be termed wings which are generally indicated in FIGURE 3 at 43 and 44. These wings each contain a pair'of rotary type axial iiow regenerator matrices, one pair being seen in FIGUR-E 6 where the upper matrix is generally indicated at 45 and the lower matrix at 46. Each matrix has a solid hub 47 non-rotatably secured to a vertically disposed shaft 48, a solid outer rim 49, and a main portion comprising many axially extending passages 51 formed of heat retaining material. Hot exhaust gases flowing through the passages during one portion of their travel will beat the matrix so that this heat may be transmitted to the compressed air flowing through the sarne passages during another portion of their travel.

Shaft 48 is supported by an upper bearing 52 and a lower bearing 53, these bearings in turn being secured to main housing 37 in a manner described in detail below. Matrices 45 and 46 are spaced vertically from each other, :but it will be noted that except for the downward extent of ducts 39, the total height of the wings 43 and 44 is no greater than that of housings 37 and 41.

Before entering a detailed description of the turbine interior, housing and duct means, it may be well to mention several other accessory components of the engine, seen in FIGURES 1 to 3. A starter 54 is mounted on the forward end of gear box housing 42, as seen in FIGURES l and 3, and adjacent the starter is an oil cooler and fan assembly 55, the air from the fan being emitted forwardly as shown by the arrows in FIGURE 1. An alternator 56, seen in FIGURE 2, and a fuel control assembly 57, indicated in FIGURE 3, are also mounted on gear box housing 42.

Gear box housing 42 has an internal wall 58 separating the gear space 59 thereof (see FIGURE 4) from compressor inlet chamber 36. The rearwardly extending wall 61 of gear box housing 42, which encloses cham-ber 36, has a flange 62, and a compressor support ring 63 is secured thereto by bolts 64. The compressor is generally indicated at 65 and comprises a compressor housing 66 secured to support ring 63 by bolts 67, and compressor blades 68 rotatably mounted within housing 66. Entrance vanes 69 extend radially between housing 66 and a rearwardly extending portion 71 on wall 58. A compressor diffuser 72 having radial ribs 73 is mounted outwardly of the radially extending portions of blades 68, and is adapted to direct the compressed air radially and then axially rearwardly. A fuel supply connection 74 is provided in compressor housing 66 leading to a fuel line 75 in one of the ribs 73. Line 75 leads inwardly to a conduit 76 formed in a member 77 centrally secured to ribs 73, and this conduit leads to an annular space 78 formed by elements secured to member 77 and disposed within an annular combustion chamber generally indicated at 79. yThis combustion chamber is of the general configuration shown in Williams Patent No. 3,077,076, dated Feb. 12, 1963, having air entrance louvers S1 and 82 together with radial passages 83 for leading heated compressed air from a chamber 84 surrounding the combustion chamber to its interior.

The entire gas turbine rearwardly of gear box 42 is supported in cantilever fashion by the gear box, and this support is primarily through compressed air housing 41. This housing is composed of two identical stampings, one of these stampings being shown in detail in FIG- URES 12 to 14, and being generally indicated at 85 in these iigures. Housing 41 is fabricated by placing two stampings 85 in facing relation with their outwardly bent edges 86 being brazed together in overlapping relation. Each stamping 85 comprises a semicircular central portion 87 having a forward edge 88 of relatively large diameter and a rear ed-ge 89 of relatively narrow diameter, portion 87 being convex outwardly so that the two stampings 85 together form a chamber surrounding the rearwardly directed exit of diffuser 72. Forward edge 88 is secured to compressor support ring 63, as seen in FIG- URE 4, and rear edge 89 surrounds and is in contact with a heated air housing which is later described.

Each stamping -85 has a pair of wings 91 and 92, seen in FIGURE 13, which extend laterally on opposite sides of central portion 87, the height of these wings being approximately the full height of edge 88, as seen in FIG- URE 14. Each wing has a vertical forward wall 93 the inner portion of which extends laterally and the outer 7 portion of which curves rearwardly so as to conform with the curvature of the forward portions of regenerators and 46. The outer wall 94 of each wing 91 and 92 is convex outwardly so as to form a chamber above each regenerator 45 and below regenerator 46, as seen in FIG- URE 6. Walls 93 end abruptly at the points indicated at 95 and 96 in FIGURE 13, and the rearwardly facing portions of wings 91 and 92 are open. The rearward edges of walls 94 terminate in fianges 97, and the sides of central portion 87 have narrow vertical walls 98, as seen in FIGURES 12 and 14. Flanges 97 and walls 90 engage the stampings which comprise main housing 37, as will later appear, this main housing being shown partially in phantom lines in FIGURE 14.

The heated air housing is generally indicated at 99 in FIGURES 4 and 6, and is made up of two identical stampings each of which is generally indicated at 101, and one of which is shown in detail in FIGURES 15 to 17. To form housing 99, two stampings 101 are placed in edge-to-edge relation with their outwardly extending flanges 102 forming a brazed 'butt joint. The central portion 103 of each stamping 101 is semicircular in shape, its forward edge 104 being of relatively large diameter and its rear edge 105 of relatively narrow diameter. The over- -all configuration of the central chamber formed by portions 103 is similar to that formed by portions 87 of stampings 85, except that it is smaller; that is, it fits within portions V87 of stampings 85 so as to form an annular space 106 therebetween which receives the compressed air from diffuser 72. As stated previously, edges S9 of stampings 85 are in sealing contact with rear edge 105 of stampings 101, thus closing the rear end of chamber 106. The arrow 107 in FIGURE 14 indicates the flow of compressed air from space 106 between housings 41 and 99 (housing 99 is shown partially in dot-dash lines in lFIGURE 14), through the chambers formed =by portions 94 of housing 41 to the regenerator matrices 45 and 46.

Each stamping 101 is provided with a pair of wings 10S and 109, indicated in FIGURE 16. The four wings of the two stampings thus form two heated-air receiving chambers, one such chamber being indicated at 111 in FIG- URE 6. Each chamber 111 is disposed between the matrices 45 and 46 of a pair of regenerators, and have openings 112 and 113 which face matrices 45 and 46 respectively. Seals 114 and 115 are disposed between openings 112 and 113, respectively, and their adjacent matrices. These seals may 'be of any appropriate construction which will permit rotation of the regenerators while preventing leakage of the heated compressed air.

The general configuration of wings 10S and 109 is best seen in FIGURE 16, the wings having forwardly facing vertical walls 116 and 117, respectively, which follow the configuration of walls 93 of stampings 05, but are spaced inwardly therefrom, as seen in FIGURE 6. The rearwardly facing vertical walls 11S and 119 of wings 108 and 109 respectively are convex rearwardly but to a lesser degree than the forward convexity of walls 116 and 117. Walls 116 to 119 all extend radially inwardly to central portion 103 of stamping 101, so that they form parts of connecting passages leading the heated air from wings 108 and 109 to the central chamber formed within portions 103 of the two mating stampings. This central chamber is indicated at 84 in FIGURE 4, and the connecting passages between wings 108 and 109 and chamber 84 are indicated at 121 and 122 in FIG- URES 15 and 17.

The compressor shaft is generally indicated at 123 and comprises an inner shaft 124 and an outer shaft 125, these shafts extending between first stage turbine wheel 126 and compressor 68 with an annular space 127 therebetween. More particularly, outer shaft extends between an outer portion of the turbine wheel hub and the compressor hub, while shaft 124 extends from an inner portion of the turbine wheel hub through the compressor and through gear box wall 5S, the gear box wall supporting a forward compressor shaft bearing 128, as seen in FIGURE 4. A rear bearing 129 is also provided for the compressor shaft, this bearing bein-g disposed within the turbine wheel hub (see FGURE 7), and the manner of supporting it is described below. An accessory drive pinion 131 is secured to inner compressor shaft 124 on the forward side of wall 58.

A power shaft 132 is provided coaxially within and spaced inwardly from inner compressor shaft 12d, a space 133 being provided between shaft 132 and shaft 125i. An intermediate bearing 134 for shaft 132 is provided within space 133, power shaft 132 extends forwardly through wall 58 with a forward bearing 135 being provided within outer compressor shaft 124 forwardly of wall 53 and rotatably supporting power shaft 132. This may be a sleeve type of bearing held in place by a nut 136 theadably mounted on the forward end of outer compressor shaft 12d. It will thus be noted that when power shaft 132 is stalled, that is, when it is not rotating because the automotive wheels 2.2 to which it is geared are held immobile, a hy .rodynatnic film of oil will still be maintained with respect to bearing because of the fact that it is supported by continuously rotating shaft 124. It does not matter, for this purpose, whether sleeve bearing 135 is fixed to .power shaft 132, compressor shaft 124, or neither. The maintenance of the hydrodynamic oil lm is quite important when shaft 132 is held immobile since it is at that time that the maximum radial force will be exerted on this shaft.

A power pinion 137 is secured to Shaft 132 outwardly of nut 136, being separated therefrom by a thrust washer 138 and being held in place by a nut 139. An axial oil passage 141 is provided within power shaft 132, this passage leading from the forward end of the power shaft through the entire shaft, stopping just short of that p01- tion which is fixed to the hub of second stage turbine wheel 142. This wheel is secured to the rear end of the power shaft by a nut 143.

The structure which, among other things7 supports the rear bearing 129 of compressor shaft 123, as well as the two rear bearings 144 and 145 of power shaft 132, will now be described. An annular outer shroud 146 is provided, this shroud being secured within the rear portion of main housing 37 in a manner described below. Second stage nozzle vanes 147 extend inwardly from this shroud, their inner ends being supported by an inner shroud 143. Outer shroud 146 extends forwardly from varies 147, surrounding first stage turbine wheel 126 and having an outwardly extending flange 149 to which is secured a burner and first stage nozzle support 151 by bolts 152. Member 151 extends inwardly and engages the exit portion of burner 79 which in turn encloses first stage nozzles 153. It may also be mentioned at this point that a heat shield 154 is provided in chamber 121 and inwardly of stampings 101, this shield being secured at its rearward end to shroud 146.

An annular axially extending connecting member 155 of relatively thin cross-sectional shape is secured at its rearward edge to the internal surface of inner shroud 148 and extends forwardly and slightly inwardly therefrom. An annular stamping 156 is secured at its outer edge to the forward edge of member 155 and extends forwardly, then inwardly and then rearwardly therefrom, its inner edge turning inwardly with a Seal 157 being disposed between the hub of turbine wheel 126 and the inner edge of stationary member 156. A similar stationary member 158 (members 156 and 150 may be identically shaped stampings) is disposed in spaced facing relation with member 156, a seal 159 being provided between the inner edge of member 158 and turbine wheel 142. The space between members 156 and 150 is partially occupied by a combined bearing support and heat sink 161. This member is a relatively massive and radially extending member of heat-conductive material, and bearings 144 and 145 are mounted in the interior of its axially 9 extending hub, bearing 129 being mounted on the exterior of the hub. A plurality of circumferentially spaced tubular members 162 extend axially between seals 157 and 159, members 162 serving to supply pressurized air to seal 159 which enhances its sealing action.

The oppositely facing edges of the outer rim of member 161 are sealed to the outer edges of members 156 and 158, thus forming an oil collection chamber 163 which exists on both sides of member 161, a cross passage 164 extending through the lower end of this member. A pair of radial drip plates 165 are mounted within chamber 163, extending from the inner portion of the reservoir partially toward the outer portion. Drip plates 165 will serve to collect oil droplets entering chamber 163 and lead this oil to Ithe bottom of the chamber where it will collect.

Radial oil passages 166 and 167 are provided in power shaft 132 for delivering oil from the passage 141 therein outwardly of bearings 144 and 145, respectively. The oil will flow from bearing 144 through a passage 168 in the hub of member 161 toward bearing 129. The oil from both bearings will ow outwardly through radial passages 169 in an enlarged portion 171 of shaft 132, which is immediately rearwardly of the elongated hub of member 161. A space 172 exists between the hub of member 161 and the hub of turbine wheel 142, the latter hub being recessed for this purpose. This annular passage 172 connects passa-ges 169 with chamber 163, so that the oil from bearings 145 wifl collect in this chamber.

One or more passages 173, seen in FIGURE 4, are provided in member 77 leading from the inner portion of pressurized chamber 196 behind burner 79 `to the outside of outer compressor shaft 125. One or more passages 174 are provided in shaft 125 adjacent passage 173 so that compressed air is led to the annular chamber 127 between outer compressor shaft 125 and inner compressor shaft 124. One or more axially extending passages 176 are provided in the hub of turbine wheel 126 leading from chamber 127 to the forward side of seal 157. Compressed air may pass this seal and enter chamber 163, thereby pressurizing the oil collected therein.

As seen in FIGURE 7, a radial passage 177 is provided in the lower end of member 161 leading inwardly from passage 164 to an axially extending passage 178 which leads forwardly to passage 168 and from there to the space 133 between power shaft 132 and inner compressor shaft 124. As noted previously, this space contains bearing 134, and a narrower forward portion of this space leads to forward bearing 135 of power shaft 132. Radial passages 180 (FIGURE 4) are provided in shaft 132 for lubricating bearings 134 and 135. It will thus be seen that during operation oil which has lubricated the rear bearings and collected in chamber 163 will be forced by the compressed air upwardly through passages 177, 178 and 168 (which of course are not subjected to centrifugal force since they are stationary) into space 133, and will travel forwardly due to the rotary effect of shaft 124, owing past axial grooves in the support for bearing 134. Drain passages 179 are provided for leading the oil from the juncture of the wide and narrow portions of space 178 to the gear box reservoir. Bearing 129 separates chamber 163 and space 133, thus receiving lubrication from these sources. The inner diameter of bearing 129 is smaller than the diameter of the bore of shaft 124 so that bearing 129 will act as a dam to prevent rearward flow of oil from space 133 into the collection chamber.

It should be observed with regard to member 161 that because of its relatively massive nature it will tend to absorb heat from the oil in chamber 163, thus minimizing the possibility of oil overheating after shutdown. It should also be noted that the maximum temperature gradient between those portions ofthe turbine in direct contact with the burned gases and the inner portions of the turbine housing will be relatively thin concentric member 155.

CTL

Th/ns, temperature differentials will not tend to cause any unwanted lateral distortions of the ports.

The spent gases leaving second stage turbine wheel 142 pass through a diffuser generally indicated at 181 into a burned gases chamber 182 rearwardly of turbine wheel 142. Diffuser 181 comprises three concentrically arranged nested members 183, 184 and 185 which form annular spaces of increasing size in a rearward direction, the members being curved radially outwardly and secured together at their rearward ends by fasteners 186. Chamber 182 is formed by a pair of identical stamp-ings, one of which is shown in FIGURES 18 to 20 and is indicated generally at 187. As previously described with respect to stampings and 101, the two stampings 187 are placed with their open sides in facing relation and their outwardly turned edges 188 forming a sealed butt joint. The central portion 189 of each stamping 187 is of semicircular shape, with its forward edge 191 being secured to the rear edge of a housing ring 192, as seen in FIGURE 4. The forward end of this ring has an outwardly extending flange which is secured to member 151 by bolts 152. As will be later seen, bolts 152 are all accessible from outside the unit, a pair of spaces 193 and 194 existing adjacent housing 37 when viewed in plan, as seen in FIGURES 3 and 4.

Portion 189 of each stamping 187 widens in a rearward direction, as seen in FIGURE 20, and has an end wall 195, the end walls of the two stampings mating immediately outwardly of exhaust diffuser 181. Each stamping further has a pair of laterally extending wings 196 and 197, seen in FIGURE 19, which connect chamber 189 with the space between the rearward portions of each pair of regenerators 45 and 46. Each pair of mating wings 196 and. 197 thus forms a chamber indicated at 198 in FIGURE 6, this chamber being of somewhat segmental shape, as seen in FIGURE 20, and extending through an arc of slightly greater than The relative areas of the compressed air and exhaust gas portions of the regenerators are of course chosen to provide optimum heat transfer eihciency for the unit. The forwardly facing portions of the vertical walls which form part of wings 196, 197 are of slightly concave shape in a forward direction so as to -conform to the shape of the walls 118 and 119 of stampings 191. They also have indentations indicated at 199 in FIGURE 20 to accommodate the shafts 48 which support and drive the regenerators. The rearwardly facing portion of the walls of wings 196 and 197 are of rearwardly convex shape and are concentric with the curvature of the regenerators, extending somewhat rearwardly therefrom as seen in FIGURE 6.

Wings 196 and 197 have segmental openings 201 and 292respectively in the walls which face regenerators 45 and 46, so that the exhaust gases may iiow outwardly from chambers 198 in upward and downward directions through the regenerator passages 51. Seals 203 and 294 are provided between wings 196 and 197 and their corresponding regenerators.

Main housing 37 is made up of two substantially identical stampings, the upper of which is shown in detail in FIGURES 9 to 11, and is indicated generally at 2&5. As in the case of the other stampings, each of the two stampings 205 has a central portion and a pair of laterally extending wings, and the two stampings are united by brazing their facing edges together. The central portion of each stamping 295 is indicated at 286 in FIGURES 9 and l0. Portion 206 is of semicylindrical shape, having a for- Y wardly facing edge 207 which is secured to ring 192 a slight distance forwardly of edges 191 of stampings 187. The enclosure formed by portions 206 of the two united stampings 295 enclose and are spaced slightly outwardly from the burned gases chamber 182 formed by portions 189 of stampings 187. This can be seen by comparing FIGURE 2O with FIGURE 11, by which it will be seen that portion 206 of each stamping 295 enlarges as it extends rearwardly, and is provided with a rearward end wall 208 spaced slightly outwardly from wall 195, a dead air space existing between these two walls. 

